docs(guide): describe directive replace:false
docs(guide): describe directive replace:false

Previous version stated `replace:false` will append template to element.
Improve description to accurately state that template will _replace_ the
contents of the current element.

Closes #2235, #4166

ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js